Method for efficiently evaluating surface energy of material

Abstract

The invention discloses a high-efficiency material surface energy evaluation method, and belongs to the technical field of material high-throughput calculation and mechanical calculation. Structural analysis is carried out on a structural file and an energy file obtained through calculation according to a first principle to obtain the number of destroyed bonds and bond energy, and then surface energy which is not relaxed is obtained through calculation. The method comprises the following steps: selecting a material system, calculating a bond length strain coefficient of the selected material system, substituting the bond length strain coefficient into a calculation formula of lattice strain energy, performing relaxation correction on unrelaxed surface energy obtained through calculation, solving an accurate surface energy result of the material subjected to surface atom relaxation, realizing efficient, accurate and rapid evaluation of the material surface energy, and completing establishment of a database. The method aims at the influence effect of coupling structure relaxation on the bond length in a classical bond fracture model, the influence rule of structure change on the material surface energy is quantitatively described through the Hooke's law, and a way is provided for achieving a high-precision surface energy rapid prediction method of multiple material systems.

Description

Technical Field

[0001] The present invention relates to the fields of material high-throughput calculation technology and mechanical calculation technology, and in particular to a method for efficiently evaluating the surface energy of a material. Background Art

[0002] Surface energy γ is an important solid-state performance parameter, and it is of great significance to reasonably evaluate the γ of materials. For crystalline solid materials, as the surface is generated, the surface atoms will lack chemical bonds due to the lack of neighboring atoms, resulting in the phenomenon of "dangling bonds". The breaking or distortion of this chemical bond will cause the energy of the system to increase. The part of the energy that increases due to the formation of the surface is the surface energy. In fact, it is difficult to accurately measure the surface energy by experimental means, so it is an effective method to calculate the size of the surface energy theoretically. The commonly used methods for accurately calculating surface energy are the first-principles calculation method by constructing a vacuum layer surface model and the semi-empirical potential model method with the help of chemical potential.

[0003] However, these two methods not only consume a lot of computing resources and time, but are also limited to calculating the surface energy of low-index surface structures with small unit cells. In addition, theoretical methods based on bond breaking models have also been widely used due to their high efficiency and simple form. In the basic bond breaking model, only the number and energy of broken bonds caused by the surface structure can be used to describe the surface energy of a specific surface, thereby greatly reducing the amount of calculation. However, it ignores the effect of surface structure relaxation on the bond length of surface atoms, which will introduce certain errors in the calculation of surface energy. Summary of the invention

[0004] The present invention aims at the needs of high-throughput computing platform and database construction for materials in the fields of catalysis and mechanical applications. By introducing the method of elastic strain energy, the accuracy of the traditional bond rupture model is optimized, and high-throughput rapid evaluation of surface energy of different crystal plane indexes of related materials is achieved, the accuracy of prediction results is improved, and the cost and development time of material design are reduced. In addition, technical support and relevant data can be provided for the subsequent efficient calculation of other properties related to surface energy.

[0005] This method aims to develop an accurate surface energy rapid evaluation model suitable for high-throughput computing platforms. By introducing Hooke's law, it can achieve rapid evaluation of elastic strain energy, which is conducive to constructing a surface energy database for different crystal plane indices of corresponding materials, and can guide the improvement of material performance, thus improving the development of advanced materials.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is:

[0007] A method for efficiently evaluating the surface energy of a material is provided, comprising the following steps:

[0008] Step 1, obtaining the structural file and energy information of the relevant material by first principle calculation; wherein the structural file includes the type and number of atoms; and the energy information includes bond energy and elastic properties;

[0009] Step 2: Based on the material structure file, a specific surface morphology is constructed to determine the number of broken type i bonds N i ;

[0010] Step 3: Based on the number N of broken type i bonds calculated in step 2 i The bond failure model is used to solve the unrelaxed surface energy of the material;

[0011] Step 4, according to the energy information of the material, the lattice strain parameters corresponding to different crystal structures are obtained by fitting epitaxy method;

[0012] Step 5, solving the elastic strain energy according to the structural information and energy information of the material obtained in step 1 and the lattice strain parameter obtained in step 4;

[0013] Step 6, using the unrelaxed surface energy of the material obtained in step 3 and the elastic strain energy obtained in step 5, solve the corrected surface energy of the material.

[0014] As a further illustration of the present invention, in step 3, the bond breaking model is as follows:

[0015]

[0016] Among them, N i is the number of destroyed type i keys, is the bond energy of type i bond and A is the surface area.

[0017] As a further illustration of the present invention, step 4 specifically includes:

[0018] Step 401, correlation coefficient and fitting parameters of face-centered cubic structure FCC, bond length strain coefficient for:

[0019]

[0020] Where B is the bulk modulus;

[0021] Step 402, correlation coefficient and fitting parameters of body-centered cubic structure BCC, its bond length strain coefficient for:

[0022]

[0023] Step 403, correlation coefficient and fitting parameters of the close-packed hexagonal structure HCP, its bond length strain coefficient for:

[0024]

[0025] Where G is the shear modulus;

[0026] Step 404, correlation coefficient and fitting parameters of pyrochlore structure, bond length strain coefficient for:

[0027]

[0028] in, is the bond energy of the RE-O type bond in the pyrochlore structure.

[0029] As a further illustration of the present invention, step 5 specifically includes:

[0030] The bond length gauge factor obtained in step 4 and Substitute the structural information and energy information of the material obtained in step 1 into the equation to solve the elastic strain energy W i ;

[0031] The equation to be solved is:

[0032]

[0033] Where E is the elastic modulus, is the bond length of type i bond, α b is the bond length strain coefficient, and A is the unit surface area.

[0034] As a further illustration of the present invention, step 6 is to obtain the material unrelaxed surface energy W obtained in step 3 and the elastic strain energy W obtained in step 5. i , the specific process of solving the corrected material surface energy is:

[0035]

[0036] Beneficial effects of the present invention:

[0037] This method aims to use high-throughput parallel methods to replace the precise calculation methods of multiple sequential iterations, develop fast and reliable calculation methods, and improve the research and development efficiency of new materials.

[0038] The effect of structural relaxation on bond length is coupled to the classical bond breaking model, and the influence of structural changes on the surface energy of materials is quantitatively described. A high-precision rapid surface energy prediction method applicable to a variety of material systems is developed. The concept of bond length relaxation parameter is proposed, and elastic strain energy is introduced to establish the function of surface energy variation with bond length extension / compression in the relaxation range. The improved model greatly improves the accuracy of material surface energy prediction and provides a reference for the relaxation scale of first-principle calculations.

[0039] Based on the theoretical model, we can achieve goal-oriented design, and with the help of high-throughput concurrent material calculation algorithms, we can establish an accurate database that helps deepen understanding and ensure performance consistency, providing data support and theoretical basis for the development of new materials. The above-mentioned embodiment method not only overcomes the shortcomings of the traditional "trial and error method", saves resources and time, but also can obtain relevant thermophysical parameters based on the first-principles calculation results, which is convenient and fast.

[0040] This method uses theoretical calculations to select samples that meet the requirements for experimental verification, which can save experimental time and resources, improve experimental efficiency, play a guiding role, and avoid blindness. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the method for efficiently evaluating the surface energy of a material provided by the present invention;

[0042] Figure 2 The bond length strain coefficient α in the embodiment of the present invention B Schematic diagram of application to different material systems. DETAILED DESCRIPTION

[0043] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0044] The present invention relates to a method for efficiently evaluating the surface energy of a material, the principle and calculation process of which are as follows Figure 1 The specific steps are as follows:

[0045] Select the material system, perform structural analysis on the structure file and energy file obtained by first-principles calculation, obtain the number and bond energy of broken bonds, and then calculate the surface energy without relaxation. Figure 2 The calculation process shown in the figure calculates the bond length strain coefficient α of the material B , and bring it into the calculation formula of lattice strain energy, perform relaxation correction on the calculated unrelaxed surface energy, solve the precise surface energy result of the material after surface atomic relaxation, realize efficient, accurate and rapid evaluation of material surface energy, and complete the establishment of the database.

[0046] Specifically: The embodiment of the present invention provides a method for efficiently evaluating the surface energy of a material, comprising the following steps:

[0047] Step 1: Obtain the structural file and energy information of the relevant material through first-principles calculation; wherein the structural file includes the type and number of atoms; and the energy information includes bond energy and elastic properties.

[0048] Step 2: Based on the material structure file, a specific surface morphology is constructed to determine the number of broken type i bonds N i .

[0049] Step 3: Based on the number N of broken type i bonds calculated in step 2 i The bond failure model is used to solve the unrelaxed surface energy of the material;

[0050] The bond destruction model is as follows:

[0051]

[0052] Among them, N i is the number of destroyed type i keys, is the bond energy of type i bond and A is the surface area.

[0053] Step 4, according to the energy information of the material, the lattice strain parameters corresponding to different crystal structures are obtained by fitting epitaxy method;

[0054] It specifically includes the following steps:

[0055] Step 401, correlation coefficient and fitting parameters of face-centered cubic structure FCC, bond length strain coefficient for:

[0056]

[0057] Where B is the bulk modulus;

[0058] Step 402, correlation coefficient and fitting parameters of body-centered cubic structure BCC, its bond length strain coefficient for:

[0059]

[0060] Step 403, correlation coefficient and fitting parameters of the close-packed hexagonal structure HCP, its bond length strain coefficient for:

[0061]

[0062] Where G is the shear modulus;

[0063] Step 404, correlation coefficient and fitting parameters of pyrochlore structure, bond length strain coefficient for:

[0064]

[0065] in, is the bond energy of the RE-O type bond in the pyrochlore structure.

[0066] Step 5, solving the elastic strain energy according to the structural information and energy information of the material obtained in step 1 and the lattice strain parameter obtained in step 4;

[0067] Specifically include:

[0068] The bond length gauge factor obtained in step 4 and Substitute the structural information and energy information of the material obtained in step 1 into the equation to solve the elastic strain energy W i ;

[0069] The equation to be solved is:

[0070]

[0071] Where E is the elastic modulus, is the bond length of type i bond, α b is the bond length strain coefficient, and A is the unit surface area.

[0072] Step 6, using the unrelaxed surface energy of the material obtained in step 3 and the elastic strain energy obtained in step 5, solve the corrected surface energy of the material.

[0073] The specific equation to be solved is as follows

[0074]

Claims

1. A method for efficiently evaluating the surface energy of a material, characterized in that: The following steps are involved: Step 1, obtaining the structural file and energy information of the relevant material by first principle calculation; wherein the structural file includes the type and number of atoms; and the energy information includes bond energy and elastic properties; Step 2: Based on the material structure file, a specific surface morphology is constructed to determine the number of broken type i bonds N i ; Step 3, solving the unrelaxed surface energy of the material based on the number Ni of broken type i bonds and the bond breaking model calculated in step 2; Step 4, according to the energy information of the material, the lattice strain parameters corresponding to different crystal structures are obtained by fitting epitaxy method; Step 5, solving the elastic strain energy according to the structural information and energy information of the material obtained in step 1 and the lattice strain parameter obtained in step 4; Step 6, using the unrelaxed surface energy of the material obtained in step 3 and the elastic strain energy obtained in step 5, solve the corrected surface energy of the material.

2. The method for efficiently evaluating the surface energy of a material according to claim 1, characterized in that: In step 3, the bond destruction model is as follows: Among them, N i is the number of destroyed type i keys, is the bond energy of type i bond and A is the surface area.

3. The method for efficiently evaluating the surface energy of a material according to claim 1, characterized in that: Step 4 specifically includes: Step 401, correlation coefficient and fitting parameters of face-centered cubic structure FCC, bond length strain coefficient for: Where B is the bulk modulus; Step 402, correlation coefficient and fitting parameters of body-centered cubic structure BCC, its bond length strain coefficient for: Step 403, correlation coefficient and fitting parameters of close-packed hexagonal structure HCP, its bond length strain coefficient for: Where G is the shear modulus; Step 404, correlation coefficient and fitting parameters of pyrochlore structure, bond length strain coefficient for: in, is the bond energy of the RE-O type bond in the pyrochlore structure.

4. The method for efficiently evaluating the surface energy of a material according to claim 3, characterized in that: Step 5 specifically includes: The bond length gauge factor obtained in step 4 and Substitute the structural information and energy information of the material obtained in step 1 into the equation to solve the elastic strain energy W i ; The equation to be solved is: Where E is the elastic modulus, is the bond length of type i bond, α b is the bond length strain coefficient, and A is the unit surface area.

5. The method for efficiently evaluating the surface energy of a material according to claim 4, characterized in that: Step 6: The material unrelaxed surface energy obtained in step 3 and the elastic strain energy W obtained in step 5 are used to calculate the i , the specific process of solving the corrected material surface energy is:

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